Track bar / drag link geometry

[EPB72]

Later can do ,,

TB 28" 13degrees DL 29" 12degrees

 

[ksagis]

TB 28" 13degrees DL 29" 12degrees

Thanks much, remind me how much suspension lift you have and if you added any drop brackets for track bar or have a dropped pitman?

 

[ksagis]

Interesting results from looking at CAD for my setup, turns out matching the angle is much more important than matching length.

First pic is drawing of current configuration with a 2" and 3" offset from track bar to drag link:

Next two pics are dropping and raising the entire axle 2"

I'm seeing roughly 1/8" of bump steer with current configuration:

@ntsqd, these results are different than yours, could you take a look at see if you see something different in the way we modelled it? Feel free to DM if easier.

 

[ksagis]

This post is matching angles of drag link and track bar, but leaving the different lengths of arms:

First pic is at ride height, the next two pics are 2" raised and lowered:

Only 0.009" of bump steer, I'm assuming it's due to different length of arms. Note that at @Yeller pointed out, my arms are longer than factory and I assume shorter arms wouldn't fare are well.

 

[ntsqd]

Last pic of mine above had the offsets at 2.5" in both directions. Moving them to 3" over and 2" down yields this:

 

[ksagis]

Last pic of mine above had the offsets at 2.5" in both directions. Moving them to 3" over and 2" down yields this:

Looks like we’re matching the 3.737” but getting a difference at the displaced conditions. Do you see anything I did wrong?

 

[EPB72]

Thanks much, remind me how much suspension lift you have and if you added any drop brackets for track bar or have a dropped pitman?

suspension lift measures 3 1/4 , no brop brackets ,no drop pittman arm,, do have JD TB riser ,,,,, OK I haven't seen this mention but I've cut and turned inner C's, 8-9 degrees.. so by doing this you raise the tie rod mine about 1-1 1/8 ,, this also seems to make the tie rod at full right and left turns to be a little closer to the axle/ diff cover and track bar bracket/ mounting bolt and possible contact before you get to steering stops.. so i did stay with SRE under knuckle ....which did give me parrallel TB and DL .....just to add I am running T Rex arms with 2 degree bushings backwards . front pinion is 2 degrees down , pretty sure ill be about 7 degrees caster but still needto get it to work and on the alignment rack..

 

[ntsqd]

Looks like we’re matching the 3.737” but getting a difference at the displaced conditions. Do you see anything I did wrong?

No, my method had an error in it's layout.

 

[Yeller]

The different lengths being parallel makes sense, the arcs are not working against each other, even though they are different arcs their differences are far less than if they were in different plains fighting each other. Been a dozen or more years since I drew all that out on the floor seeing how they intersect and move lol

 

[davisjstone]

I don't mean to hijack, but lots of in depth info here and I thought it might be the right place rather than a new thread. My bronco is almost back on the road, so no real word experience with how it handles...yet...soon after a long 2.5 years of a steep learning curve. The lift and front and front end work was done by PO long ago.

74 with 3" lift (by measuring from axle to frame) and 1" body. Drop pitman arm and stock track bar drop bracket. Street only. Haven't messed with the front end at all, but from what i'm reading, my track bar and drag link are way off?

Do I need a track bar drop bracket at a minimum? My research says a riser is better as the drop bracket may stress the frame, but my concern is that may put the track bar parallel with dragline, but way off plane?

Suggestions or any other glaring issues?

 

[DirtDonk]

Yes. Just on general principle, if you have a drop Pittman arm and no drop track bar bracket (or riser), your angles will be off.
Which seems to be borne out by your pictures.

Is that an old school axle truss I see there under your differential? Looks a little unusual, but that’s what it looks like.
If so, that’s pretty cool and I haven’t seen one of those in a long time.

What are your intended uses for the bronco?
What size tires will you have?
These answers will go a long way to deciding whether you need a riser or a drop.
As I mentioned before though, I think even in this thread, a drop bracket is simple, inexpensive, can be installed by the vehicle owner, even without any fancy tools, and is generally perfectly reliable for most uses.
And while I hate to spend more of your hard earned money, an adjustable track bar is still not a bad idea.
It’s not strictly necessary, at least for centering the axle, because the drop track bar bracket will also accomplish this for the most part.
But the adjustable track bar does two things. It lets you fine tune in the axle’s center position, just in case the track bar drop is not enough. And it also lets you adjust the upper eye angle, to allow to more naturally fit in the track bar bracket.
The latter makes installation easier, puts less stress on the bar and bracket, and will certainly extend the life of your upper track bar bushing.

So my recommendation is to install a track bar drop. Make sure to get one for a 3-ish inch lift, to match your pitman arm.
Once it’s bolted in, and you verify the angles are reasonably parallel, you can then drive it to somebody that can finish the installation by welding it to the frame/original bracket.

 

[Yeller]

@davisjstone, @DirtDonk is correct. The easy solution for your issue is a drop bracket for the track bar. I still prefer a riser but with your street only use it will make it drive well and not be expensive or too difficult to install. The best option would be to convert to the tie rod to the top of the knuckle, replace the pitman arm with a stock one and use a riser off the axle. That’s a lot of extra work for a minimal, if any gain for your desired outcome, the changes wouldn’t be noticeable doing normal street driving unless you are very in tune with how vehicle dynamics feel. I feel with where your build currently sits that is the best option, if you need to replace all of the steering linkage, track bar bushings, etc and have the capability to to the work the flip might be the way to go but is certainly more work and money.

 

[ntsqd]

I dunno, I'd be really tempted to just put a stock pitman arm on it and see how that looks and drives. The steeper angle will result in more lateral translation of the front axle during suspension movement, but if it drives straight and behaves itself within how you expect to drive it on the street I'd call it good. Free, and not much work if you happen to have a stock pitman available.

OTOH, if it misbehaves then yeah, what they ^^^ said.

Sometimes I think that dropped pitman arms are something that should have never been invented. My FSB came to me with one on it. It's TTB has been cut and modified for ~4" lift, so I'm guessing that's why the dropped arm. It drove terrible! I ordered a stock pitman from JBG to try (didn't have one laying around) and that fixed most of the problem. It now drives like a typical squirrelly TTB instead of a really squirrelly and semi-unpredictable TTB.

 

[davisjstone]

Yes. Just on general principle, if you have a drop Pittman arm and no drop track bar bracket (or riser), your angles will be off.
Which seems to be borne out by your pictures.

Is that an old school axle truss I see there under your differential? Looks a little unusual, but that’s what it looks like.
If so, that’s pretty cool and I haven’t seen one of those in a long time.

Not really sure if it's an axle truss or what? I've never seen one on another bronco. Seems to be like a skid to save the axle and diff from getting hit. Not really necessary for my street only application. Here's another picture. It bolts to radius arm caps

What are your intended uses for the bronco?
What size tires will you have?

I'll be running 285/70/17 tires

These answers will go a long way to deciding whether you need a riser or a drop.
As I mentioned before though, I think even in this thread, a drop bracket is simple, inexpensive, can be installed by the vehicle owner, even without any fancy tools, and is generally perfectly reliable for most uses.
And while I hate to spend more of your hard earned money, an adjustable track bar is still not a bad idea.
It’s not strictly necessary, at least for centering the axle, because the drop track bar bracket will also accomplish this for the most part.
But the adjustable track bar does two things. It lets you fine tune in the axle’s center position, just in case the track bar drop is not enough. And it also lets you adjust the upper eye angle, to allow to more naturally fit in the track bar bracket.
The latter makes installation easier, puts less stress on the bar and bracket, and will certainly extend the life of your upper track bar bushing.

I was wondering if I would need an adjustable track bar. Haven't measured if the axle is centered but I will. Sounds like even if the track bar is close to center there are other benefits to the adjustable track bar.

So my recommendation is to install a track bar drop. Make sure to get one for a 3-ish inch lift, to match your pitman arm.
Once it’s bolted in, and you verify the angles are reasonably parallel, you can then drive it to somebody that can finish the installation by welding it to the frame/original bracket.

Thanks.

 

[davisjstone]

@davisjstone, @DirtDonk is correct. The easy solution for your issue is a drop bracket for the track bar. I still prefer a riser but with your street only use it will make it drive well and not be expensive or too difficult to install. The best option would be to convert to the tie rod to the top of the knuckle, replace the pitman arm with a stock one and use a riser off the axle. That’s a lot of extra work for a minimal, if any gain for your desired outcome, the changes wouldn’t be noticeable doing normal street driving unless you are very in tune with how vehicle dynamics feel. I feel with where your build currently sits that is the best option, if you need to replace all of the steering linkage, track bar bushings, etc and have the capability to to the work the flip might be the way to go but is certainly more work and money.

Roger that!
I know a TRO conversion and riser may be ideal, but I hate throwing $ at something I may never really use. I don't no much about doing the TRO and what all is required? Seems like the TRO conversion will end up costing much more in time and $ than a drop bracket and if there will likely be no noticeable benefits for my application then why throw money at it.

 

[davisjstone]

I dunno, I'd be really tempted to just put a stock pitman arm on it and see how that looks and drives. The steeper angle will result in more lateral translation of the front axle during suspension movement, but if it drives straight and behaves itself within how you expect to drive it on the street I'd call it good. Free, and not much work if you happen to have a stock pitman available.

OTOH, if it misbehaves then yeah, what they ^^^ said.

Sometimes I think that dropped pitman arms are something that should have never been invented. My FSB came to me with one on it. It's TTB has been cut and modified for ~4" lift, so I'm guessing that's why the dropped arm. It drove terrible! I ordered a stock pitman from JBG to try (didn't have one laying around) and that fixed most of the problem. It now drives like a typical squirrelly TTB instead of a really squirrelly and semi-unpredictable TTB.

Hmm. Unfortunately, I don't have a stock one laying around. The cost of a new stock pitman vs a track bar drop is about the same, so I hate to buy a stock pitman only to find I need to go back to the drop pitman and then have to buy the track bar drop.